package com.xn.myproject.loader;

import android.content.res.Resources;
import android.graphics.Bitmap;
import android.graphics.BitmapFactory;
import android.util.Log;

import java.io.FileDescriptor;

/**
 * 作者：tracyxia
 * 时间：11/7/15/22:52
 * 描述：
 * 版本：
 */
public class ImageResizer {
    private static final String TAG = "ImageResizer";

    public ImageResizer() {

    }

    public Bitmap decodeSampledBitmapFromResource(Resources res, int resId, int reqWidth,
                                                  int reqHeight) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeResource(res, resId, options);

        //Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
        return BitmapFactory.decodeResource(res, resId, options);
    }

    public Bitmap decodeSampledBitmapFromFileDescriptor(FileDescriptor fd,
                                                       int reqWidth, int reqHeight) {
        final BitmapFactory.Options options = new BitmapFactory.Options();
        options.inJustDecodeBounds = true;
        BitmapFactory.decodeFileDescriptor(fd, null, options);
        //Calculate inSampleSize
        options.inSampleSize = calculateInSampleSize(options, reqWidth, reqHeight);
        //Decode bitmap with inSampleSize set
        options.inJustDecodeBounds = false;
        return BitmapFactory.decodeFileDescriptor(fd, null, options);

    }

    public int calculateInSampleSize(BitmapFactory.Options options, int reqWidth, int reqHeight) {
        if (reqWidth == 0 || reqHeight == 0) {
            return 1;
        }

        final int height = options.outHeight;
        final int width = options.outWidth;

        Log.d(TAG, "origin,w" + width + " h=" + height);
        int inSampleSize = 1;

        if (height > reqHeight || width > reqWidth) {
            final int halfHeight = height / 2;
            final int halfWidth = width / 2;

            while ((halfHeight / inSampleSize) >= reqHeight
                    && (halfWidth / inSampleSize) >= reqWidth) {
                inSampleSize *= 2;
            }

        }

        Log.d(TAG, "sampleSize:" + inSampleSize);
        return inSampleSize;
    }
}
